Conventionally, a spatial map showing data on each location in a predetermined space is widely used. Examples of the spatial map include a topographic map obtained through surveys and a railroad route map.
Moreover, in recent years, a spatial map in which displayed data changes with time (hereinafter, referred to as a spatiotemporal map) is also widely used. Examples of the spatiotemporal map include a weather map and a traffic map.
In order to improve the accuracy of data in the spatiotemporal map, it is desired to collect more types of data at a finer spatial density and at a shorter time interval. For that purpose, however, it is necessary to increase the number of sensors and the like to be used for data collection and increase the frequency at which the sensors and the like acquire data, which results in a rise in required costs and an increase in consumption power.
In contrast, Patent Literature 1 proposes a technology in which, in a case where an event to be notified is detected within a monitoring area by a photo-sensor and a microwave sensor, a camera is turned on to start transmission of images obtained by imaging the monitoring area, and after the event is finished, the camera is turned off to stop transmission of images. Use of this technology allows power saving to be achieved.